学术报告
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A Constructive Approach to L0-Penalized RegressionWe develop a constructive approach to estimating sparse, high-dimensional linear regression models. The approach is a computational algorithm motivated from the KKT conditions for the -penalized least squares solutions. It generates a sequence of solutions iteratively, based on support detection using primal and dual information and root finding. We refer to the algorithm as SDAR for brevity. Under a sparse Rieze condition on the design matrix and certain other conditions, we show that with high probability,the estimation error of the solution sequence decays exponentially to the minimax error bound in steps; and under a mutual coherence condition and certain other conditions, the estimation error decays to the optimal error bound in $O(/log(R))$ steps,where is the number of important predictors, is the relative magnitude of the nonzero target coefficients.刘妍岩 教授 (武汉大学 数学与统计学院)致远楼101室2019年5月30日上午10:00
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Covariate-Adjusted Regression for Distorted Longitudinal Data with Informativ...In many longitudinal studies, repeated response and predictors are not directly observed, but can be treated as distorted by unknown functions of a common confounding covariate. Moreover, longitudinal data involve an observation process which may be informative with a longitudinal response process in practice. To deal with such complex data, we propose a class of flexible semiparametric covariate-adjusted joint models. The new models not only allow for the longitudinal response to be correlated with observation times through latent variables and completely unspecified link functions, but they also characterize distorted longitudinal response and predictors by unknown multiplicative factors depending on time and a confounding covariate.赵兴球 教授 (香港理工大学应用数学系)致远楼101室2019年5月30日上午9:00
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An Introduction to Theta FunctionsTheta functions are special functions of two complex variables, which is a central subject in the study of mathematics. Theta functions play a key role in many branches of mathematics, including algebraic geometry, number theory, modular forms, partial differential equations and combinatorics. In this talk, I will give a brief introduction to theta functions with emphasis on theta function identities.刘治国 教授 (华东师范大学)致远楼101室2019年5月29日 15:00-16:00
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Completely Monotonic Fredholm DeterminantsIn this talk we discuss some monotonicity questions related to Fredholm matrices and operators. A function $f(x)$ is called completely monotonic if $(-1)^mf^{(m)}(x)>0$. It is known that the expectation of having $m$ eigenvalues of a random Hermitian matrix in an interval is a multiple of $(-1)^{m}$ times the $m$-th derivative of a Fredholm determinant at $/lambda=1$. In this work we extend the positivity to half-real line $(-/infty,1]$, and we also study the completely monotonicity of some special functions which arise as Fredholm determinants.张瑞明 教授 (西北农林科技大学)致远楼101室2019年 5月29日 16:00-17:00
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The Q-Normal Distribution and Q-Hermite PolynomialsWe survey results on q-analogue of the normal distribution and the corresponding orthogonal polynomials.Prof. Mourad E.H. Ismail (University of Central Florida and King Saud University)致远楼101室019年5月29日 14:00-15:00
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Complex Short Pulse and Coupled Complex Short Pulse EquationsIn this talk, we will investigate a complex short pulse equation and its two-component generalization. First, we will derive them starting from Maxwell equations. Then we will study their various soliton solutions such as bright, dark, breather and rogue wave solutions by using Hirota’s bilinear method and Darboux transformation method.冯宝峰 教授 (美国德克萨斯大学大河谷分校)致远楼103室2019年5月29日(周三)15:30-16:30
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Apparent Singularities of D-Finite SystemsWe generalize the notions of ordinary points and singularities from linear ordinary differential equations to D-finite systems. Ordinary points and apparent singularities of a D-finite system are characterized in terms of its formal power series solutions. We also show that apparent singularities can be removed like in the univariate case by adding suitable additional solutions to the system at hand. Several algorithms are presented for removing and detecting apparent singularities. In addition, an algorithm is given for computing formal power series solutions of a D-finite system at apparent singularities. This is a joint work with Manuel Kauers, Ziming Li and Yi Zhang.陈绍示 副研究员 (中国科学院 数学与系统科学研究院)致远楼103室2019年5月24日14:00-15:00
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On the Existence of Conic Kahler-Einstien MetricLog Fano manifold are generalization of Fano manifolds, and the canonical metrics on them are conic Kahler-Einstein metrics. I will talk about the existence of such metrics on log K-polystable log Fano manifolds.王枫 副教授 (浙江大学)致远楼101室2019年5月23日14:00-16:00